Vivianite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameVivianite
Chemical FormulaFe3(PO4)2·8H2O
Mohs Hardness1.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorbluish white
Cleavageperfect on {010}
Fracturefibrous
Specific Gravity2.65
Colorscolorless, blue, blue-green, green, dark blue, black
Transparencytransparent
Type LocalityMullica Hill, Gloucester County, New Jersey, USA
Mineral Groupphosphates
Usescollector
Associated Mineralspyrite, siderite, apatite, quartz, clay minerals
Rarityuncommon
Description
The image displays a cluster of elongated, prismatic Vivianite crystals, exhibiting a deep blue-green color and a vitreous luster, some appearing almost black due to their depth of color.
Geological Context
Vivianite typically forms as a secondary mineral in reducing environments within sedimentary deposits, such as bog iron ores, fossil bones, shells, or wood, where iron and phosphate are present. It can also occur in pegmatites and hydrothermal veins.
